ML19309H749
| ML19309H749 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 05/08/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Pilant J NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8005190672 | |
| Download: ML19309H749 (1) | |
Text
bCC N 8005190 h7D CEitTRAL FILES POR:HQ UNITED STATES
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NUCLEAR REGULATORY COMMISSION LPOR I~.
REGloN IV
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/Mi 611 RYAN Pt.AZA oRIVE. SUITE 1000 qg{C i
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'v May 8, 1980 3
Dockat No.
50-298 Nebraska Public Power District ATTN:
J. M. Pilant, Director Licensing & Quality Assurance Post Office Sox 499 Colu= bus, Nebraska 68601 Gentlemen:
The enclosed IE Information Notice provides early notification of an event that may have safety significance. Accordingly, you should review the Infor=ation Notice for possible applicability to your facility.
No specific action or response is requested at this time; however, contingent upon the results of further staff evaluation, a 3ulletin or Circular recom-mending or requesting specific licensee actions may be issued.
If you have questions regarding this matter, please couract me.
Sincerely, p..
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,; ; )l,{,.,l i' 4; f,. p t~
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Karl V. Seyfrit, /
Director
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Enclosures:
1.
IE Information Notice No. 80-20 2.
List of Recently Issued 5
IE Information Notices cc:
L. C. Lessor, Superintendent Cooper Nuclear Station Post Office Box 98 3rownville, Nebraska 68321
SSINS No.:
6870 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8002280671 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C. 20555 IE Information Notice No. 80-20 Date:
May 8, 1980 Page 1 of 3 LOSS OF DECAY HEAT REMOVAL CAPABILITY AT DAVIS-BESSE UNIT 1 WHILE IN A REFUELING MODE Description of Circumstances:
On April 19, 1980, decay heat removal capability was lost at Davis-Besse Unit 1 for approximately two and one-half hours.
At the time of the event, the unit was in a refueling mode (e.g., RCS temperature was 90 F; decay beat was being removed by Decay Heat Loop No. 2; the vessel head was detensioned with bolts in place; the reactor coolant level was slightly below the vessel head flanges; and the manway covers on top of the once through steam generators were removed).
(See Enclosure A, Status of Davis-Besse 1 Prior to Loss of Power to Busses E-2 and F-2 for additional details regarding this event.)
Since the plant was in a refueling mode, many systems or components were out of service for maintenance or testing purposes.
In addition, other systems and components were deactivated to preclude their inadvertent actuation while in a refueling mode.
Systems and components that were not in service or deactivated included:
Containment Spray System; High Pressure Injection System; Source Range Channel 2; Decay Heat Loop No. 1; Station Battery IP and IN; Emergency Diesel-Generator No. 1; 4.16 KV issential Switchgear Bus C1; and 13.8 KV Switchgear Bus A (this bus was energized but not aligned).
In brief, the event was due to the tripping of a non-safeguards feeder breaker in 13.8 KV Switchgear' Bus B. Because of the extensive maintenance and testing activities being c'nducted at the time, Channels I and 3 of the Reactor Protec-o tion System (RPS) and Safety Features Actuation System (SFAS) were being ener-gized f.om only one source, the source emanating from the tripped breaker.
r Since the SFAS logic used at Davis-Besse is a two-out-of-fou which the loss (or actuation) of an of all four output channels (i.e.,
loss of power to Channels 1 and 3 b DUPLICATE DOCUMENT Channels 2 and 4.
The actuation of Decay Heat Loop No. 2, the operatin Entire ac<nunent Previously entered into system under.
Since the initiating event was a los were actuated (i.e., Level 1 - High ANO bh tion; Level 3 - Low Pressure Injecti g
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